In order to meet the demand for wireless data traffic soring since the fourth generation (4G) communication system came to the market, there are ongoing efforts to develop enhanced fifth generation (5G) communication systems or pre-5G communication systems. For the reasons, the 5G communication system or pre-5G communication system is called the beyond 4G network communication system or post long term evolution (LTE) system.
For higher data transmit rates, 5G communication systems are considered to be implemented on ultra-high frequency bands (mmWave), such as, e.g., 60 GHz. To mitigate pathloss on the ultra-high frequency band and increase the reach of radio waves, the following techniques are taken into account for the 5G communication system: beamforming, massive multi-input multi-output (MIMO), full dimensional MIMO (FD-MIMO), array antenna, analog beamforming, and large scale antenna.
Also being developed are various technologies for the 5G communication system to have an enhanced network, such as evolved or advanced small cell, cloud radio access network (cloud RAN), ultra-dense network, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, coordinated multi-point (COMP), and interference cancellation.
There are also other various schemes under development for the 5G system including, e.g., hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC), which are advanced coding modulation (ACM) schemes, and filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA), which are advanced access schemes.
Meanwhile, MIMO technology increases channel capacity within limited frequency resources by using multiple antennas and provides channel capacity theoretically proportional to the number of antennas by multiple antennas having an excellent scattering environment.
However, MIMO technology has a limited space and area where antennas may be installed, and the inter-antenna interval has a significant influence on communication capability. That is, as the inter-antenna interval decreases, radio channels present a higher correlation. In particular, when antennas have the same polarization, radio channels have a significantly high correlation, and interference between radio channels reduces reliability and data transmission ratio of data communication.
Accordingly, various polarization directions of antennas need to be used in order to increase channel capacity while decreasing the area where multiple antennas are installed. This is why interference between radio channels may be decreased when antennas have multiple polarizations.
MIMO technology requires a precoding task for previously coding data in order to efficiently transmit data. Further, a data precoding rule represented as a matrix is called precoding matrix, and a set of precoding matrixes is called codebook.
Although various codebooks have been suggested for operation of non-beamformed reference signals, there is no suggestion as to efficient codebooks regarding operation of beamformed reference signals. Therefore, a need exists for low-complexity, high-performance schemes for generating codebooks when operating beamformed reference signals.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.